Most of us don’t have the authority that comes with 40 years of being Miss Manners, but no matter who you are it can be near impossible to pry anyone away from their mobile playthings. (Harder still: Are your friends or partner more into their smartphone than they are into you?)

The problem of looking at our devices nonstop is both social and physiological.

The average human head weighs between 10 and 12 pounds, and when we bend our neck to text or check Facebook, the gravitational pull on our head and the stress on our neck increases to as much as 60 pounds of pressure. That common position, pervasive among everyone from paupers to presidents, leads to incremental loss of the curve of the cervical spine. “Text neck” is becoming a medical issue that countless people suffer from, and the way we hang our heads has other health risks, too, according to a report published last year in The Spine Journal.

Social psychologists like Amy Cuddy claim even standing in a confident posture, with your head up and shoulders back, can heighten testosterone and cortisol flow in the brain, preventing much of the above. So, why aren’t we heeding these signs? It might be simple denial.

Inattentional blindness is a problem

Some 75 percent of Americans believe their smartphone usage doesn’t impact their ability to pay attention in a group setting, according to the Pew Research Center, and about a third of Americans believe that using phones in social settings actually contributes to the conversation.

But does it?

Etiquette experts and social scientists are adamantly united: Nope.

That “always-on” behavior that smartphones contribute to causes us to remove ourselves from our reality, experts said. And aside from the health consequences, if we’re head down, our communication skills and manners are slumped, too. But, ironically, that might not be how most of us see ourselves.

“We think somehow that this antisocial behavior is not going to affect me,” said Niobe Way, professor of applied psychology at New York University.

Ms. Way studies technology’s role in shaping adolescent development. These head-down interactions take us away from the present, no matter what group we’re in, she said. And it’s not just a youth problem. It’s ingrained, learned, copied and repeated, much of it from mimicking adults. When kids see their parents head down, they emulate that action. The result is a loss of nonverbal cues, which can stunt development.

“What’s happening more and more is we’re not talking to our children,” Ms. Way said. “We put them in front of the tech when they’re young, and when we’re older, we’re absorbed in our own tech.”

You’ve seen it: Think of how some parents deal with screaming toddlers. “Here kid, take this iPhone and go to town,” according to Ms. Way — not, “Let’s talk this out, what seems to be the problem, son?’”

She added: “We think, ‘Somehow my kids will know what’s a good and bad interaction, they’ll have empathy.’ But when I go upstairs into my son’s room and seven teens are all looking at their phones, none of them saying a word, there’s all sorts of disengagement happening. It’s not Facebook that’s the problem, it’s how we’re using Facebook.”

All ages are affected

A study in 2010 found that adolescents ages 8 to 18 spent more than 7.5 hours a day consuming media. Since then, our digital addictions have continued to, in some ways, define our lives: In 2015, the Pew Research Center reported that 24 percent of teenagers are “almost constantly” online.

“Mobile devices are the mother of inattentional blindness,” said Henry Alford, the author of “Would It Kill You to Stop Doing That: A Modern Guide to Manners.” “That’s the state of monomaniacal obliviousness that overcomes you when you’re absorbed in an activity to the exclusion of everything else.”

The social scientist Sherry Turkle analyzed 30 years of family interactions in her book “Alone Together: Why We Expect More From Technology and Less From Each Other.” She found that children now compete with their parents’ devices for attention, resulting in a generation afraid of the spontaneity of a phone call or face-to-face interaction. Eye contact now seems to be optional, Dr. Turkle suggests, and sensory overload can often mean our feelings are constantly anesthetized.

Facebook’s former president, Sean Parker, recently said the platform was designed to be addictive and to “consume as much of your time and conscious attention as possible,” which he characterized as boosting our self-esteem, ever-present in the dopamine hit of likes.

“It literally changes your relationship with society, with each other,” he said. “It probably interferes with productivity in weird ways. God only knows what it’s doing to our children’s brains.”

That said: You’re probably reading this story on a mobile device right now. And that’s O.K.! (As long as you’re not behind the wheel.) We’re not here to tell you to throw away your iPhone and abandon digital media. But like many addictions, admitting a problem is the first step to treatment. And, mercifully, the fix isn’t anti-tech — it’s pro-conversation, according to Dr. Turkle.

Make an effort to interact with people

Digital detoxes have never been so popular, but they’re no cure-all, and realistically, there simply isn’t a black-and-white fix.

The simplest answer for all of us is biblical: Do unto others — and maybe do it without clutching your smartphone. Next time you’re in the checkout lane or stopped at a red light, look around. How many people are really there with you?

“Actual human beings, in the flesh, take precedence,” Ms. Martin chided. “To ignore people you’re with is rude, whether you ignore them for virtual friends or distant friends by snubbing them.”

It sounds so obvious it almost borders on stupid. But like Dr. Turkle’s hope of building dialogue, not denigrating the digerati, it’s an obvious dialogue we’re not having enough of.

Mr. Alford, who used to write a monthly manners column for The New York Times, described the issue as a “monomaniacal obliviousness” of being absorbed in an activity to the exclusion of the rest of the world.

“To treat the person standing in front of you as secondary to your phone, is usually, as the kids say, a micro-aggression,” he said.

Many Silicon Valley pundits go to war when anyone so much as suggests that tech’s merits aren’t uniformly positive. But in light of the brutal schoolyard that social media has become, that approach now appears moot.

Young or old, we’re all a generation of literal test cases. Etiquette, manners, body language, the way we respond, interact and even look is changing. We’re missing a whole life happening a mere 90 degrees above our smartphones. Start looking up.

“Never be the first person in the group to whip out his phone,” Mr. Alford said. “Don’t be Patient Zero.”

Correction 1/30/2018: An earlier version of this article misstated the number of car accidents attributed to the use of smartphones. About one quarter of car accidents in the United States are caused by texting and talking on the phone while driving, not solely by texting.

Adam Popescu is a writer living in Los Angeles who contributes frequently to the Times. He can be reached on Twitter at @adampopescu